Process of recovering hydrocyanic acid.



FELD.

PRGUESS o? mcovmm HYDROGYMUC Aww.

P?LCATION ELED PEB. 27.1909. u

Patients@ May E8, w99.

Y Amande@ WALTHER FELD, OF HNNlNGEN-GN-TlilE-EHENE, GERMANY.

PROCESS Oli? HECVERKNG HYDRANIC ACID.

m, eeecoo.

Patented. may is, ieee.

Application mec February er, isos. senin smesoel.

To-'all whom t concern:

Be it known that I, WALTHEB FELD, e subl ject of the King ofyPrussia and the German Emperor, of Hnningenan-the-Rhinein the 'German Empire, have invented nev.l and liseful Improvements in Processes of Recovering Hydrocyanic Acid, of which the following is a specilicetion.

, ln o rder to obtain hydrocyamic acid from metallic cyamds, such as iron cyanide and Others, they have been distilled with acids,

but, by this process the yield of hydrocynnic acid is small and in addition te hydrocyanic acid, products lof decomposition and condensetion 'are formed, and port of the metallic cyanid remains undecomposed. Hydrocranic .ncicl has else been obtained by heating solutions of cyanide with salt solutions, but

'All

decomposed so esto yield only hydrocyeuic this process is applicable only to the trentrnent of alkali or earth alkali cyanids, and not to iron cyends and the like.

According to my invention, metallic ry snide, such as iron cysnids (alkali or eerth alkali 'or other ferrocyenids," ferricyenids, Prussian blue, and the like) nrc completely acid by treatingthem while hot, in e' solid or `damp state (but not in the 'form of a colu tion) with steam together with enacid in such manner that While the reaction proceeds, the reacting muss is not covered by the liquid, orliquids. in form of liquors or vapors periodically or continuously to the cyanid to be distilled. Instead of acids .l nay use acid seits, .or such salts als will 'when heated in nV solid or moist state with steam, yield acid by decomposition. Suitable acids for the purposes-ol my invention are hydrochloric, hydrolironiic, n.1'- tric, sulfuric, phosphoric and silicio scid, end suitable salts are ell the acid salts of the cbove mentioned acids end their neutrel or bnsic seits with einmonia, ningnese, elsif mina, manganese, zinc, iron, copper, or leed.

V The use ol" such salts, instead of acide, has the advantage that the course of the reection .no tree scid is lormed, which, 1% formed Such acid mcy be added would contaminate the hydrocyenic scid. The reaction is complete if erven less salt is usedtlian is equivalent to the cyanid to be.

decomposed.- ll, for exemple,V ammonium chloriol in the presence of steam act upon heated lrussinn blue, iron ch'lorid is formed and' c mixture of hydrocyanic acid is distilled. The react-ion may be expressed se follows:

The iron chlorid, under-the inlluence ol' steam, yields iron hydroxid and llydrochloric acid, thisl acting upon undecomposed cyanid. This reaction maybe expressed as follows:

rcel', sito s rf, (on), Hei.

The sume reaction tclies'plcce il other of the above mentioned salts be used.

In order to prevent acid vapors being mixed with the hydroeyenic acid :it the end of the reaction, the vapors of the scid ot the reaction ere absorbed by basic compounds oi the salts employed. This may. be accomplished in any suitable manner, for instance by ndding such basic compounds of the salts (hydrctcs or cerbonctes lof megnesis iron exid and the like) tothe reacting mixture. These basic substances if heated, will absorb only the vapors of the reaction acids and not hydrocyenic acid. The use of such basic compounds with the reacting mixture will not interfere with the completeness of the rece t1on,even 1f less acid; or less basic,

neutral, or arid, salt be used than is equiv ne' m seance sorb the same. ln this case also it is possibley ing mixture (containing the metallic cyanid and acid or acid-yielding compound)` may be heated by heating the reaction vessel or by passing a heated gas through the reacting mixture or both. A

It the reaction vessel be heated sufficiently to vaporize Water, the necessary steam for the process maybe obtained bymerely addingswater to the reacting mixture.

This Water may convenientlyv carry'the acids or saltsl insolution, vBut 'if Water be used in this mannen'the amount employed and the degree ofheat must be so regulated that the reacting mixture is never covered by liquid, butvmerely moistened, and that the when heated.

A l reaction.l y

Water'is ya orized the moment it comcsin contact Wit the Walls .of the reaction vessel. Instead of eithe.71 Water or steam, a com- -pound'may beA used which will yield steam Essie salts or neutral hydrates ofglnetals are suitablelor this purposec Care must 'be taken that the chamber' in Which the reaction takes placeis always nlled with steam, which, in addition to reacting as described, will act as a carrier for the.

hydrocyanic acid formed by the reaction.

Such carrying medium is necessary in order4 to` avoid 'local saturation of hydrocyanic` ac ld vapors in the reacting mass, 4which might interfere with the completion of the From the foregoing descri tion the method 'of Working for-'each case Wi 1 be readily unn derstood. 'ihe particular method of Worklng, the temperature of ,l decomposition (which in any case mustbe' abovelOOC centi'grade), and the arrangement of the appa-- ratus, must depend on ythe nature of. the metallio cyanid "to be decomposed, the', distillation agent (acid, acid salt, or acid-yielding salt,) used, andthe purpose 'for Which the hydrocyanic acid obtained vis to. be used'. The said hydrocyanic acid may be used for any process. lt maybe absorbed by hydrates o1' carbonates of allralies or earth allialies in a solid or liquid form, or it may be used for the cbtainment of ferrocya-nids or ier ricyanids or of organic nitrpgen compounds of any com osition.

The Tello ing'is an example of how the ,process according to this inventiony may be performed in the treatment of Prussian blue With chlorid of magnesium, but l do not -limit myself to these compounds, nor to the proportions and temperatures hereafter given, as they may be varied according to 4each particular case.l The parts" are* by Weight. The Prussian blue is presumedto be in a dam state, containing about '50 per cent. of so id FeFesCyl. One hundred parts of thePrussian blue are'mixed with a quantity of magnesium chlorid, (in, solid crystals, or in a fused condition, 'or in con'n centrated solution) ecpiiva'lentl to about twenty parts of MgCl2. A greater,'or smaller, amount does not influence the completeness of the reaction,.but has only an accelerating, or retardin ,influence This reaction may be expresse( as follows:

2Mgc12v+ eine nel ange. y The reaction of the hfd-rochloric acid with the Prussian blue is t ye same as above inv dicated. To obtain the hydrcyani'c acid nesia may be added. By mixing, .the

agents vbecome liquid, butno hydrocy'anic' acid is formed, even if the mixture be Warm.'

Any suitable apparatus may be used for the distillation cil the mixture which will 'allow vthe said mixture to be gg'raduallyl charged, heated and tested. For example, a revolving apparatus which willfallow continuous'wolil'ig, such as is shown in the accompanying drawingmiay beJused.

'A ,horizontal apparatus A with a revolving worm inside, is here shown. The apparatus. Amay be -keptunder' a slight 'vacuum bythe free of hydrochloric acid, ve parts nf/magexhaustM in order lto avoiddaner by escape.

` oli of the hydrocyanie acid-L The steam and the reacting mixture trai/'ei in Opposite directions. External heatfmay be applied to the reaction chamber byany suitable means for instance by a series'ofcBunsen burners Q.

The farther the reacting mixture advances in 4the apparatus, the more it is heated and ygives oil Water vapors till the mixture has advanced to that part ofthe apparatus where hydrccyanc acid is distilled Vat a tempera- '.lhe s eedat which the mixture passes throng the apparatusand the heating are so regulated that the reactionis completebefore, or when the mixturesrrisfesz at the 'end4v where steam and gas enter. t this and of the apparatus a discharge pipe C leads the exhausted ma'terialintoja receptacle D corrture between. '150 and 350 centigrade.-v

stood that the mention of the metallic .cya-

eeasee taining water, or a solution of magnesium chlorid'. 'lhe material, by fallin into this liquid, is'cooled to suchA a degree t. at no iurther reaction takes place, and in case any undecomposed cyanid should accidentally have remained in the mass, danger to the operators is avoided. 'lhe liquid extracts fromv the solid mass any magnesium chlorid remaining undecom osed which is thus regenerated. 'lhe'insolu le iron oxid is separated from theliquid by filtration, or decantation, and can be used for the extraction of cyanogen" from coal gases and the like. Il the process be carried on as hereinbei'ore described, most of the magnesium chlorid will be regenerated so that the reaction will be effected at the cost only ofthe steam.

The gas and steam carrying the hydrocyanic acid leave the reaction chamber through thecpipe F and enter the absorption apparatus 1 This comprises a series of superposed chambers filled with caustic soda which enters by the pine The gases are washed by this and the vdrocyanic acid and steam are absorbed, the Waste gases passing oll` to the exhaust M through the pipe L. The cyanid of soda solution. is'collected in the vessel li.

'lhe process may be usedior' the decomposition of any metallic cyanid, also for doun ble cyanids for instance. for ferroand ferricyanids of alkalies, earth alkalies, ammonia, iron and other metals and bases.

ln the following claims it is to be undernids being in a solid condition includes a moist condition other than a solution; that "steam means either steam as such I{superheated, or not.) or steam contained in a gas, or gases, or steam derived from acompound yielding steam when heated with the acid, or salt, and that acid lmeans acid liquor or vapors and that salt" means a basic, ncutral or acid salt which7 when heated with steam, will yield an acid, or acid vapor.

l claini l, The process of obtaining hydrocyanic acid from metallic cyanids in a solid state which consists in subjecting the latter at a temperature above l 000 (l. and in the prescmfc ol steam to the action of acid and maintain.- ingr the reacting,r mass at least in part above the reaction liquid.

The process of obtainingP hydrocyanic acid from metallic cyanide in a solid state which consists in. subjecting the latter at a temperature above i000 (l. and in the presence of steam to the action of a salt yielding acid du ringr the reaction and maintinnira"r the re- :1i-,tiner mass at least in part above the reaction liquid.

Il, The process of obtaining hydrocyanic acid from metallic cyanids in a solid state which consists in subjecting the'latter at a i temperature above l 00 C. and in the presence of steam to the action oi acid and maintaining the reacting mass at least in part above the reaction liquid, absorbing the acid vapors Withlint affecting the hydrocyanic acid.

Il. The process of obtaining hydrocyanic acid 'from metallic cyanide in a solid state which co sists in subjecting the latter at a temperature above 1000 C. and in the presence oi steam tothe action ci a salt yieldingr acid during' the reaction and maintaining t e reacting mass at least in part above the re action liquid, and absorbing; the acid vapors by basic compounds of said salts. i

The process of obtaining hydrocyanic acid from metallic cyanids in a solid state which consists in subjecting the latter at a temperature above i000 C. and in the presence of steam to the action oi acid less in proportion than is equivalent to the metallic eyanid and maintaining the reacting mass at least in part above the reaction liquid.

6. The process olf obtaining hydrocyanic acid. from metallic cyanids in a solid state which consists in subjecting the latter at a temperature above 100 C. and in the presence of steam to the action of acid intimately mixed with said oyanid. and maintaining the reacting mass at least in part above the reaction liquid.

7. The process oi obtaining; hydrocyanic acid from metallic cyanids'in a solid state which consists in subjecting the latter at a temperature above 1000 C. to the action of acid and a substance yielding steam under heat and maintainingr the reacting mass at least in part above the reaction liquid.

S. The process of obtaining; hydrocyanic acid from metallic cyanide' in a solid state which consists in subjecting the latter at a temperature above 100 (l. and in theprcsence of steam to the action of acid and maintaining the reacting mass leest in part above the reaction liquid.

S. The process of obtaining hydrocyanic acid from metallic cyanids in a solid state which consists in subjecting the latter at a vtemperatnrc above 1.000 (l. and in tliepresence oi steam and gras to the .action oi acid and maintaining the reacting' mass at least in part above the reaction liquid. l

l0, The processe-obtaining hydrocyanic acid from metallic cyanids in a solid state which consists in subjecting the latter at a 'temperature above 1000G. and in the presence of supcrhcatr-:d steam to thc action of acid. and maintaining the reacting mass at least in part ahovethe reaction liquid.

l l. The process of obtainiiig l ydrocyanic acid from metallic cyanide in a solid state wl'iich consists in subjectingT the latter at a temperature above 1000G. and in the presence of superheated steam and. a gas to tbe action oi acid and maintainingr the reactingr mass at least in part above the reaction liquid.

12. The proc-ess of obtaining bydrocyanic esegui Y acid from metallic cyanids in at solid state l n'testimon'y whereof I have signed my which consists in subjecting the letter in a name to this specification in the `presence of reaction vessel to the action of acid in the two subscribing Witnesses.

presence of steam, ,externally heating said WALTI-IER FELD.V Vessel during the reaction and maintaining Witnesses: the reacting mass at leest in part above the WOLDEMAR HAUPT,

reaction liquid at a, temperature above 10()o C. HENRY HAsPER. 

